document.write( "Question 182870: A driver sets out on a 20-mile trip. When he has gone halfway he finds he has averaged 25 mph. At what speed must he travel the rest of the way to make his overall average speed for the trip 40 mph? \r
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Algebra.Com's Answer #137280 by Edwin McCravy(20056) $\"\"$ $\"About$

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A driver sets out on a 20-mile trip. When he has gone halfway he finds he has averaged 25 mph. At what speed must he travel the rest of the way to make his overall average speed for the trip 40 mph?
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document.write( "In order to average 40mph on a 20 mile trip, the time his\r\n" );
document.write( "total trip must take is found by:\r\n" );
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document.write( "So in order to average 40mph he must arrive half an hour after he left.\r\n" );
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document.write( "Now we'll calculate how much of that half hour he has already used up \r\n" );
document.write( "during the first half of his trip, or 10 miles:\r\n" );
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document.write( "Therefore he has only  or  or  of\r\n" );
document.write( "an hour left to travel the remaining 10 miles.  Now to find\r\n" );
document.write( "out what rate he must travel in that remaining hour,\r\n" );
document.write( "we use:\r\n" );
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document.write( "Edwin

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